Manufacture of artificial materials



Patented Sept. 7, 1937 UNITED STATES PATENT OFFICE Serial No. 755,420. In Great Britain December 14, 1933 This invention relates to improvements in the manufacture of artificial filaments; threads, yarns, foils and similar materials containing organic derivatives of cellulose, and particularly to processes wherein the artificialmaterials are subjected to stretching operations,

Processes are already known wherein artificial filaments and other materials containing organic derivatives 'of cellulose are subjected to stretching operations in order to improve their tensile strength, resistance to delustring, or other properties. Thus in U. S.' Patent No. 1,709,470 there are described processes wherein artificial filaments are subjected to a stretching operation' beyond their elastic limit and are thus rendered resistant to the delustring action of hot aqueous 'media, and U July 16, 1929, describes the treatment of. filaments or threads containing cellulose acetate or during their travel from one point to another.

I have now discovered that organic basic compounds, particularly lower aliphatic amines and basic 'cyclic compounds containing nitrogen in the nucleus, e. s. pyridine, which are relatively volatile, are very valuable agents for use in stretching operations, since "such compounds have a rapid penetrating and softening action on the a suitable condition for stretching. Organic bases have a saponifying action on cellulose acetate and other organic derivatives of cellulose. The softening action which they exert upon the materials, however, takes efiect before any saponification or at least any substantial saponification occurs, and in carrying out the process of the present invention the conditions of treatment are controlled so that stretching is effected and the saponifying agent is removed or its action neutralized, for example by reducing its temperature, before any saponification or any undesired degree of saponification results.

According to the present invention, therefore, artificial filaments, threads, yarns, ribbons, foils and similar products containing cellulose acetate or other organic derivative ofcellulose are softened by means of media containing organic bases, particularly lower aliphatic amines and basic cyclic compounds containing nitrogen in the nucleus, and subjected to a stretching operation.

Examples of organic bases which are particularly suitable are mono diand tri-methylamines and cthylamines, piperidine and pyridine. Diamincs. such as ethylene diamine, monoand S. applications. No. 378,684 filed according .to the-preseii that the sap'onifying action, other organic derivatives of cellulose which com.- prises subjecting them to a stretching operationmaterials, and thus very quickly bring them into I '1 Claims; (01. 8-20) di-methyl ethylene dlamine and propylene di- 1.2.3-triamino-propane may also be amine, and usedfor the purposes of the :present invention. Other organic basic compounds, for example quinoline and aniline, may be employed.' The compounds may also contain other groupings, particularly groupings which tend to increase their solubility in aqueous or alcoholic media such as, for example, hydroxy groups. Thus; ethanolamines and other alkylolamines may be employed and also other hydroxy amino compounds, for

example axy-diamino-p-hydroxy propane. Ureaarid substituted ureas, e. g.. diethyl urea, tetraphe'nyl urea, thiour'ea and guanidinemay also be employecL'thoughpreferably solutions of normally gaseous" or liquid substances are used.-

As is stated above; the conditions of'treatment v if any, of the basic compounds is inhibited by removal of the com-' poundsor otherwise before ithas taken eilect to any undesireddegree. Thus the saponifying action may be prevented or reduced by carrying out the stretching operation at low temperatures or with dilute solutions or by allowing the base to act only for a short time. While, in general, it' is preferable that treatment with the softening agents of the present invention should be carried out at normal temperatures or less, the processes may, if desired, be effected at higher temperatures, e. g. up to 406'0 C, or even more, and in such cases the softening period and/or concentration may, of course, be reduced.

t inventionwill be such 7 Y The softening agents of the present Invention are preferably applied to the artificial materials in aqueous or aqueous alcoholic media, though the invention is,not limited thereto and other suitable media, e. g, hydrocarbons, may, it desired, be employed. Moreover, while bath treatments are, in generaLthe best methods of treating the artificial materials with the-softening agents of the present invention, other methods may, if desired, be employed, 'for example the materials may be sprayed with the softening agent or passed over wicks, rollers or other surfaces which carry the agent.

The materials may be softened in the form of hanks or other packages and subjected to a stretching operation in this form, but, in general. the best method of carrying out the process of the present invention is to soften and stretch the materials during their travel from one point .to another, for example from a wet or dry spinning apparatus to a winding or winding and twisting device, or during their travel from one package to another, for example in a bobbin to bobbin operation, or in a winding operation carried out on materials proceeding from a cheese or cake. In the'case of foils, films and similar products,

stretching'may be longitudinal or transverse, or

like, may be carried out-in stages, e. g. by passing the materials insubstanti'ally non-slipping contact with a series of rollers rotating at successively increasing peripheral speeds, and if desired frest periods may be inserted between the stretching stages, e. g. by contacting the materials with one or more pairs of rollers the peripheral speeds of the rollers in each pair being the same. Furpresent inventioncomprises uniformly impreg-f;

ther, in the case of artificial filaments and the. like considerable advantages, particularly in repect of the production of -materials of "uniform properties, may be attained by softening and stretching a number of the materials simultaneously in "warp formation, i. e. in parallel alignment in the formof a sheet.

One method of carrying out the process of the nating the materials with the base-under such conditions that the base has substantially 'no.. softening action upon them, and then subjecting thelimpregnated materials for a short period of time to conditions such that the'softening actionf' of the'baseis'increased tosuch an-extent that. the desired degree of stretching can be-effected.' Thus. artificial filaments may be passed through: a bath containing-a solution of a suitable'or-.

ganic'base at a temperature such that it has substantially no softening action uponjthe materials, and they may then be passed'rapidLv through a heated chamber to bring 'the softening action of the base into efiect and simultaneously stretched. After stretching the base may be removed by washing the materials with a suitable solvent for the base. Preferably the diluent employed in making up the solution of the organic base is more volatile or at least not substantially less volatile under the stretching conditions than the organic base itself, so that the concentration of the base on the materials during stretching tends to increase or at least does not substantially decrease. Suitable diluents which may be employed are water, benzene, toluene, ethyl ether and other ethers and relatively volatile petroleum hydrocarbons. The best results according to this method are in general obtained when the organic base and it concentration in the solution in which it is applied are so chosen that during stretching the base is present on the materials in a concentration approaching but slightly less than that at which it is a solvent for the materials under the stretching conditions.

The tension to bring about the stretch may be applied to the artificial materials simultaneously with the application of the softening agent of the present invention, or means may be employed whereby the stretching tension is restricted to the portion of the materials whichhas reached a sufiiciently softened condition. For example, in the case of artificial filaments and similar products, they may be passed round or over a series of rollers or sets of rollers, and softening may be -carried out between the first two rollers or sets of rollers, which rotate at the same peripheral speed, and the succeeding rollers or sets of rollers may rotate at increasing peripheral speeds so that The stretching operation, particu-.

the materials are stretched. Again, a single soft- 'ening treatment may be applied 'to the materials in order to bring them to the condition which is requisite for stretching, or a series of softening treatments maybe applied. In many cases it is advantageous to apply at least two scftening treatmentsthe'first treatment being such as to bring the artificial materials to a softened 7 state which is slightly less than that-required for concentration but at diiferent tcmperatu'res the temperature of the first so utionbeing a few degrees, for example 5-10 C. below that of the "second solution.-

As stated above organic baseswhich are rela-- 'tively; volatile are particularly suitable for the purposes of the. present invention and in such cases' in particular, and especially when 'open 1 baths are employed, it is advantageous to cover :-the bath'with a layer offan oil or other suitable liquid-which is'iimmis'cibletherein, e. g., as is described in U; S.--'application S. No. 690,122 filed ai'sth septeniber,1933.

Stretching of" he artificial materials may be fefie'cted" according .to the prescnt invention by.

for example," t e-200% of the original length of the materials-f or :igby' considerably greater amounts." In this manner mater'ialshaving an improved tenacity -niay'be obtained. 'The' artificial materials treated according to the present invention may be subjected to shrinking operations to improve their extensibility either prior'to or subsequent tofthe stretching process ofv the present'invention. Suitable shrinking processes are described in U. S. applications S. Nos. 6ll,2i0 filed'13th May. 1932, and 672,805 filed. 25th May, 1933. Shrinking may be carried out either continuously with the process of the present invention or as a separate operation.

While, as stated above, the primary object of the present invention is the stretching of artificial materials in order to increase their tenacity, yet the invention does not exclude a simultaneous saponification when it is desired that such should take place. Simultaneous saponification and stretching by means of the organic bases employed according to the present invention has the advantage that the treatment medium contains only one activeagent, and recovery of the agent or the making up of the bath is thus considerably The following examples are given in order tc illustrate the invention, but it-is to be understood that theydo not limit it in any way:-

Example 1 Example 2 A large number of cellulose acetate yarns ar stretched in a manner similar to that describe in Example 1, except that a 50 to 60% aqueou solution of piperidine at 20 to 25 C. is employer through a chamber heated yarns.

, Example 3 z A large number of cellulose acetate yarns are stretched in a manner similar to that described in Example 1', except that a.'40-45% aqueous solu- 5 tion oi trimethylamineat -30 C. is employed.

Example 4 e A large number of cellulose acetate yarns in the form of a warp are passed through a bath consist- 10 ing of ethyl ether, waterand 35% pyriwashed, dried and wound.

The invention is of particular value in the case of artificial materials containing cellulose acetate, and .especially cellulose acetate having an 25 acetyl content of from to 54 up to 56 or 58% calculated as acetic acid. The cellulose acetates employed in the manufacture of the artificial materials may be cellulose acetates of relatively low viscosity, for Example 12 to 15 or 20 calculated on the basis of a 6% solution in acetone compared with 'glycerine as 100, or they may have considerably higher-viscosities, for Example 40, 50 up to to or even more. Cellulose acetates of this character may be obtained by the 35 processes described in U. S. Patent No. 1,708,787.

' .The process of the present invention is also applicable to other organic derivatives of cellulose, for example cellulose propionate, butyrate and nitro-aeetate, cellulose laurate, palmitate, benzo- 40 ate and other esters andmixed esters of cellulose, methyl, ethyl,. butyl and benzyl cellulose and other cellulose ethers or mixed ethers, and ethyl cellulose acetate, oxyethyl cellulose acetate and other cellulose ether-esters. Cellulose esters of 45 higher. organic acids are relatively resistant to .sa'ponification bythe organic bases employed according to the present invention, while cellulose ethers are practically unafiected and moredrastic softening conditions may therefore be employed, '50 ii -desired, -without causing saponification or undue saponification of the materials.

What I claim and desire to secure by Letters Patent is:-

On issuing from the chamber they are.

1. Process for the treatment of artificial filaments, threads, foils, films and similar materials, having a basis of cellulose acetate, which comprises softening the materials with a medium containing a lower aliphatic amine and subjecting the softened materials toa stretching operation.

2. Process for the treatment of artificial filaments, threads, foils, films and similar materials having a basis of cellulose acetate, which comprises softening the materials with a medium containing a methylamine and subjecting the softened materials to a stretching operation.

3. Process for the treatment of artificial filaments, threads, foils, films and similar materials having a basis of cellulose acetate, which comprises soft'ening the materials with a medium containing an ethylamine and subjecting the softened materials to a stretching operation.

' 4. Process for the treatment of artificial filaments, threads, foils, films and similar materials having a basis of organic derivatives of cellulose,

which comprises impregnating the artificial materials with a medium containing .an organic base which is normally a fluid under such conditions that no substantial softening takes place and then rapidly heating the materials so as to bring them into a sufficiently softened condition for stretching and stretching them.

5. Process in accordance with claim 4 wherein theorganic base is a basic cyclic compound which contains nitrogen in the nucleus.

6. Process for the treatment of artificial filaments, threads, foils, films and similar materials having a basis of cellulose acetate, which comprises impregnating the artificial materials with a, medium containing a lower aliphatic amine under such conditions that no substantial softening takes place and then rapidly heating vthe materials so as to bring them into a sufiiciently softened condition for stretching and stretching them. v

7. Process for the treatment of artificial fila- .ments, threads, foils, films and similar materials having a basis of organic derivatives of cellulose, comprising impregnating the artificial materials with a medium containing an organic base selected from the group consisting of pyridine and piperidine under such conditions that no substantial softening takes place and then rapidly heating the materials so as to bring them into a sufficiently softened condition for stretching and stretching them.

HENRY DREYFUS. 

